Apple lle problem

[DontFryTomato]

Hello everybody,

I just got an Apple lle that does not boot. I've read about the garbage screen problem, including here, but what is on my screen (attached) is a systematic pattern, which also includes "Apple ll". The pattern does not change after power-cycling. The computer initializes (there is the beep) but does not show the prompt. It reacts to control-open apple-reset (there is the beep again), but no other keys as far as I can tell. It does not try to spin the floppy drive. The behavior is the same with all the extension cards removed. I have read about reseating all the chips but have not tried this yet, hoping that maybe somebody can narrow down the list of potential culprits. Thank you!

On a separate note, coming from the world of PCs, I watched with disbelief the previous owner, who thought that the problem is the floppy drive card, taking it out of the slot and putting it back with the power on. The apple didn't care, or at least showed no sign of distress. Is this how it is supposed to be done in the Apple world?

 

[HoJoPo]

Hold down ctrl, open apple and closed apple, then press reset. This will run the built in self test. I suspect you have a faulty RAM chip, the self test should point it out.

 

[Wayne Stewart]

And don't install or especially remove any card while the power is on. While itis possible, there is a very good chance of shorting something.

 

[DontFryTomato]

HoJoPo, thanks for the advice. I tried to run the self test, but there were no changes reflected on the screen, so I do not know if the self test even started. I also turned the system off and turned it back on while holding the open and closed apple keys (this also should initiate the self test?). The result is almost the same, except there is no "apple ll" at the top...

To Wayne Stewart: I certainly will not, thanks.

 

[Kool65]

The fact that it displays "Apple" and beeps means the CPU should be working. I'd suspect you've got a RAM problem or data/address line problems. I'd probably start by re-seating the CPU & ROMS and see if that makes any difference. Are the RAM chips socketed? If not they are probably the original RAM chips which most likely will need replacing in any case. Before you take on changing the RAM I'd go ahead and re-seat all other socketed chips.

I recently replaced the RAM in my Apple IIe which had similar output to yours, you'll see in the attached picture the original RAM that I think is always soldering in on the IIe. You can replace these with generic 4164 RAM chips.

 

[HoJoPo]

HoJoPo, thanks for the advice. I tried to run the self test, but there were no changes reflected on the screen, so I do not know if the self test even started. I also turned the system off and turned it back on while holding the open and closed apple keys (this also should initiate the self test?). The result is almost the same, except there is no "apple ll" at the top...

To Wayne Stewart: I certainly will not, thanks.

Another way to force the self test to run is to unplug the keyboard cable from the main board, then power it on. This was how they burn-in tested the motherboards during production. You could also try holding the open and closed apple keys down while powering it on.

 

[DontFryTomato]

Thanks for the advice.

It looks like I have the early version of the main board (1982). The RAM chips are socketed, I reseated them all without any changes. I have two replacement chips on the way... I also reseated the CPU and all the ROM chips - no changes... and broke one decoupling capacitor in the process (is there a gentle way of removing a chip?) - still no changes )

I will wait for the RAM chips to arrive. In the meantime, was it customary to sign apple ii cases (photo)?

 

[Kool65]

Are you sure it's a IIe and not a II ? The first screenshot you posted has "Apple ][" at the top, so I'm thinking it might be a II. In that case it would explain the socketed RAM. Also I don't think the II had the built-in diagnostic.

I use a flat blade jewelers screwdriver to gently lift the chips, alternate lifting from one side then the other so as to lift it out evenly. It's quite easy once you get the hang of it. There are also dedicated chip removal devices available. Best if you are grounded when removing the chips also or at least touch a ground point before starting on each chip.

Can't say I've seen any signed internally like that but seen plenty engraved on the outside case, especially if they use to belong to a school.

 

[HoJoPo]

Are you sure it's a IIe and not a II ? The first screenshot you posted has "Apple ][" at the top, so I'm thinking it might be a II. In that case it would explain the socketed RAM. Also I don't think the II had the built-in diagnostic.

I use a flat blade jewelers screwdriver to gently lift the chips, alternate lifting from one side then the other so as to lift it out evenly. It's quite easy once you get the hang of it. There are also dedicated chip removal devices available. Best if you are grounded when removing the chips also or at least touch a ground point before starting on each chip.

Can't say I've seen any signed internally like that but seen plenty engraved on the outside case, especially if they use to belong to a school.

The unenhanced Apple //e has "Apple ][" as the banner at start up. The enhanced //e has "Apple //e".

 

[Kool65]

@HoJoPo, Yes now you mention it I remember that now. I guess all of the //e's I've come across lately have had the ROMs upgraded.

 

[DontFryTomato]

And here is the prompt. There was one faulty memory chip. The self test returned "kernel ok". Thanks for all the suggestions.

The next issue is probably the disk controller. On start-up the 5'25 floppy makes the correct "seeking" sounds but never stops spinning, no matter if there is a floppy disk inside. I believe the drive itself is not at fault because I have a spare drive that works, and it does exactly the same. The disk is freshly written Lode Runner that works on my apple iic. This is the same controller that the original owner removed and inserted with the system on. He also did it at an angle to show me that at a certain position the drive starts spinning. So I think he shorted something...

 

[Kool65]

And here is the prompt. There was one faulty memory chip. The self test returned "kernel ok". Thanks for all the suggestions.

Nice, and only one.

He also did it at an angle to show me that at a certain position the drive starts spinning. So I think he shorted something...

I cringe at the thought of that , I think it's highly likely the card is damaged, and wouldn't surprise me if something on the board is too. From memory I believe the chips on the controllers are in sockets and are fairly generic so shouldn't be too difficult to change them out. Or if you can find another controller that might be the easiest (I see them for sale quite often). If you happen to have a logic probe (or scope) you could test the various chips to narrow down the problem.

 

[daver2]

With the disk controller you can read (and check) the contents of the bootstrap PROM from the Apple itself. With one of my disk controllers the PROM contents didn't read correctly. I did, however, observe that some of the PROM was 'repeating' I found that one of the pins of the PROM had been 'eaten' through and had become open circuit. A quick pin repair and I had the correct contents reading once again.

Because I had a damaged pin on the PROM - I checked the other ICs, and found exactly the same 'eaten pins' on some of the other ICs. These were standard TTL parts - so were replaced cheaply.

The motor constantly running fault could be due to the PROM bootstrap - but it could also be associated with the NE556 or the 9334.

There is a good website here related to the disk controller card: https://www.bigmessowires.com/2021/11/12/the-amazing-disk-ii-controller-card/.

As most of the devices are standard TTL parts - they can easily (and cheaply) be replaced. The only 'difficult' items would be the two (2) PROMS.

Do you have a logic probe or a multimeter to do a bit of diagnosis? You could measure the logic levels on the pins of the NE556 (D2), 9334 (C2) and 74LS132 (A2) and post the results. This would enable me to at least point you in the right direction.

Dave

 

[DontFryTomato]

Dave, many thanks for the detailed post and the article. After reading it I thought the controller is generally doing what it is supposed to do: finding track 0 and trying to read from it. I did not know that the ROM size is only 256 bytes, which explains the absence of any code that would handle a situation where the data is not being read. So I thought I should check if the problem is somewhere else. It was a trivial one. It turns out my floppy drives are on a continuum when it comes to their ability to read. Only the iic drive that wrote Lode Runner can read it, whereas there are a couple of diskettes written by the same drive that also work in my spare. This is how I found that the disk controller works. The drive that came with the iie could not read any of the floppies I tried so far, but this is not a big deal.

Thank you everyone for your help. I am sure I will run into other issues and will seek your advice again.

 

[daver2]

No problem.

Dave

 

[wyattwong]

It will be easier to troubleshoot if you got another spare Apple IIe computer so you can swap the RAM chips one by one for testing.